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SYSTEMS PREPARATION QUESTIONS 2007 -7 |
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Trains are often controlled by traffic lights. These
tell the train driver when to stop and when it is safe to move the train
forwards. The lights are controlled by the outputs of a microcontroller
circuit (seen below). The table shows the operating cycle. |
Outputs 0 to 5 are used to control the sequence of lights |
What are the logic levels of the outputs when they are switched on by the microcontroller |
ANSWER |
HIGH / ON / TRUE / 1 |
Complete the table below to show the output bit pattern required to run the traffic lights for one cycle. Begin with light A on GREEN and light B on RED. |
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